EXPRESSION OF THE ANTIOXIDANT GENE NKEF IN THE CENTRAL-NERVOUS-SYSTEM

Free radicals and the oxidative stress they impose can cause serious i njury in the nervous system and contribute to pathology associated wit h a wide variety of degenerative and traumatic disorders. In this stud y, we examined the expression of an antioxidant defense gene, nkef, in human tissue and isolated populations of rat brain cells using Wester n and Northern blot analysis. NKEF protein was expressed in human brai n, liver, kidney, muscle, and lung. The human endothelial cell line EC V expressed a 25-kDa band in addition to the 22-kDa band normally obse rved. In the central nervous system, a 22-kDa NKEF band was present in cortical gray and white matter, hippocampus, cerebellum, and spinal c ord in roughly similar amounts. Expression of NKEF-A and NKEF-B subtyp es was evaluated by Northern analysis of cultured cell types from embr yonic rat brain. Astrocyte and microglia expressed both 22- and 25-kDa bands, whereas cortical neurons and oligodendrocytes contained only t he 22-kDa protein band. Northern blot analysis of these cell types rev ealed low levels of NKEF-A message in neurons and oligodendrocytes, an d relatively low levels of NKEF-B in microglia. Differential expressio n of these antioxidant defense genes may contribute to the selective v ulnerability of brain cell types to specific kinds of oxidative stress .